Anammox process is happening to be in the center of interest for several years. Implementing partial nitrification/Anammox process into main stream of wastewater would result in a great improvement of sustainable technologies for reducing nitrogen in environment. However, Great chalange fo Anammox bacteria in main stream is the low temperature which is a strong inhibiting factor for them. In this study pilot-scale MBBR reactor was operated to investigate the influence of low temperatures in Anammox process. Two different phases operated at 13 and 16°C were investigated during five months. SAA, OUR and online measurements were used to observe process capacity in low temperatures. Deammonification process was found to be stable in 13°C. Moreover, Anammox bacteria capacity to convert nitrogen to nitrogen gas was found in even 5°C. Satisfactory results for Deammonification process in low temperatures may result in future application of Anammox process in full-scale plant for main stream of wastewater.

An important source of freshwater in arid lands is found in groundwater aquifers that are recharged after storm events. However, most of the precipitation is lost due to evaporation and only small fractions actually recharge the aquifers. The construction of dams along wadi channels enables the retention of stormwater, however the reservoirs are still subject to huge evaporative losses and contamination. In this study, the hydraulic properties of a dunefield in western Saudi Arabia are evaluated in order to determine the feasibility of designing a stormwater storage aquifer storage and recovery facility using the dune sands as a natural medium and design recommendations are addressed. The accurate estimation of hydraulic conductivity of unlithified sediments such as dune sands has become very important in the design of natural filtration projects, including aquifer recharge and recovery systems. Therefore, a comparison and selection of methods for the determination of the hydraulic conductivity from grain size distribution found in the literature was done. An improvement to these equations based on measurements on dune samples was obtained.

Nanofluids consist of nanometer-sized particles or fibers in colloidal suspension within a host fluid. They have been studied extensively since their creation due to their often times anomalous and unique thermal transport characteristics. They have also proven to be quite valuable in terms of the scientific knowledge gained from their study and their nearly unlimited industrial and commercial applications. This research has expanded the science of nanofluids into a previously unexplored field, that of cryogenic nanofluids. Cryogenic nanofluids are similar to traditional nanofluids in that they utilize nanometer-sized inclusion particles; however, they use cryogenic fluids as their host liquids. Cryogenic nanofluids are of great interest due to the fact that they combine the extreme temperatures inherent to cryogenics with the customizable thermal transport properties of nanofluids, thus creating the potential for next generation cryogenic fluids with enhanced thermophysical properties. This research demonstrates that by combining liquid oxygen (LOX) with Multi-Walled Carbon Nanotube (MWCNT) inclusion particles, effective thermal conductivity enhancements of greater than 30% are possible with nanoparticle volume fractions below 0.1%. Three distinct cryogenic nanofluids were created for the purposes of this research, each of which varied by inclusion particle type. The MWCNT's used in this research varied in a number of physical characteristics, the most obvious of which are length and diameter. Lengths vary from 0.5 to 90 microns and diameters from 8 to 40 nanometers. The effective thermal conductivity of the various cryogenic nanofluids created for this research were experimentally determined by a custom made Transient Hot Wire (THW) system, and compared to each other and to more traditional nanofluids as they vary by type and particle volume fraction. This work also details the extensive theoretical, experimental, and numerical aspects of this research, including a rather detailed literature review of many of the salient sciences involved in the study of cryogenic nanofluids. Finally, a selection of the leading theories, models, and predictive equations is presented along with a review of some of the potential future work in the newly budding field of cryogenic nanofluids.

The properties and behaviors of charge transport mechanisms in highly insulating polymers are investigated by measuring conduction currents through thin film samples of low density polyethylene (LDPE). Measurements were obtained using a constant voltage method with copper electrodes inside a chamber adapted for measurements under vacuum and over a wide range of temperatures and applied fields. Field-dependent behaviors, including Poole-Frenkel conduction, space charge limited current (SCLC), and Schottky charge injection, were investigated at constant temperature. These field-dependent mechanisms were found to predict incorrect values of the dielectric constant and the field dependence of conductivity in LDPE was not found to be in agreement with SCLC predicted behavior. A model of thermally assisted hopping was a good fit at low applied fields and produced activation energies within the accepted range for LDPE. Low applied field measurements over the range of 213 K to 338 K were used to investigate two prominent hopping conduction mechanisms: thermally assisted hopping and variable range hopping. The observed temperature dependence of LDPE was found to be consistent with both thermally assisted hopping and variable range hopping. Activation energies determined for the range of temperatures were consistent with values reported in the literature for LDPE under similar conditions. A third aspect of charge transport behavior is a bulk response with time dependence. Conductivity behavior is examined in relation to transient current behavior, long time decay currents, and electrostatic discharge. Comparing charging and discharging cycles allowed qualitative separation of polarization and multiple trapping behaviors.

Graphene is a form of carbon with unique thermal and structural properties, giving it high potential in many applications, from electronics to driveway heating. Advanced fabrication techniques putting small, graphene-like structures in a polymer matrix could allow for incorporation of some of the benefits of graphene into very lightweight materials, and allow for broader commercialization. Measuring the thermal properties of these thin-film samples is a technical capability in need of development for use with the specific specimens used in this study. Relating those thermal properties to the microstructural composition was the focus of this work. Several conclusions could be drawn from this study which will help guide future development efforts. Among these findings, it was found that increasing carbon content only improves thermal and electrical conductivity if the samples were of low porosity. Samples of approximately identical overall carbon content and void content had higher thermal conductivity if some carbon nanotubes were added in place of graphite. Nanotubes also appeared to reduce variability in thermal conductivity between pressed and unpressed samples, allowing for more predictable properties in fabrication.

Thermal transport properties are critical for applications ranging from thermal management to energy conversion. Passive thermal management has been an area of study for over a century and has only grown as technology has advanced because it requires no additional energy to remove heat. Changing the nanostructure of the materials involved in passive heat transfer methods, either by geometric changes or stoichiometric changes, can greatly improve the effectiveness of this heat transfer method. In order to explore this further, this work employs LAMMPS molecular dynamics (MD) simulation software to calculate the lattice thermal conductivity (λp) of a nanoparticle (NP) and material used indifferent passive heat transfer methods after either modifying their geometry or stoichiometry. The NPs this work will simulate are single-wall carbon nanotubes (SWCNTs), which have been well known for high λp, and their applications in improving thermal conductivity in matrix materials. The material this work will simulate is magnesium silicide (Mg2Si), a thermoelectric material. Thermoelectric materials, in general, become more efficient in converting heat into electrical power as their λp decreases. λp will be calculated for SWC-NTs of varying lengths, diameters, and at varying equilibration temperatures (Teq). λp will be calculated for samples of pure Mg2Si and Mg2Si with off-stoichiometry over a range of Teq values. Two methods will be used to induce the off-stoichiometry: atomic silicon (Si) substitutionals, and Si NPs. A range of stoichiometric ratios will be applied to the material by both methods, and then λp will be calculated for each of these cases. This is done so as to observe which method of stoichiometric change, given the same stoichiometric ratio, decreases λp greater, and, therefore, causes Mg2Si to be a better thermoelectric material. It is expected that increases in length will increase the λp of the SWCNT, while increases in diameter and Teq will decrease λp. It is expected that increases in atomic percent (a/o) Si and Teq will decrease λp regardless of the method of stoichiometric change, and that the Si NP method will decrease λp more than the atomic Si substitutional method.

The effects of pentachlorophenol (PCP), a widely used pesticide, on the electrical characteristics of lipid bilayer membranes has been studied. When a small amount of PCP (even at a concentration of a few micromoles per liter) is present in the electrolytic solution surrounding the membrane, the electrical conductivity of the membrane significantly increases. The present work was concerned with detailed measurements of the changes in the conductivity caused by PCP under chemically controlled conditions. The experimental results were analyzed to determine the permanent species in the membrane, and an attempt was made to correlate the data with existing models of transport.

In this project the author has attempted to determine the specific conductance of a gel of known composition; the changes, if any, of conductance in a gel as it sets; and the changes in conductance due to the diffusing of an electrolyte through the gel.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第20410号 / 工博第4347号 / 新制||工||1674(附属図書館) / 京都大学大学院工学研究科合成・生物化学専攻 / (主査)教授 北川 進, 教授 松田 建児, 教授 杉野目 道紀 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第21443号 / 理博第4436号 / 新制||理||1637(附属図書館) / 京都大学大学院理学研究科化学専攻 / (主査)教授 北川 宏, 教授 竹腰 清乃理, 教授 吉村 一良 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM